Up to now, an ejector-type refrigeration cycle that is a vapor compression refrigeration cycle having an ejector as a refrigerant depressurizing device has been known.
For example, Patent Document 1 discloses an ejector-type refrigeration cycle having an accumulator which is a low-pressure side gas-liquid separation device for separating a refrigerant that has flowed out of an ejector into gas and liquid, and storing an excess liquid-phase refrigerant. The ejector-type refrigeration cycle further depressurizes the liquid-phase refrigerant separated by the accumulator, causes the liquid-phase refrigerant to flow into an evaporator, and draws the gas-phase refrigerant separated by the accumulator into a compressor.
In the ejector-type refrigeration cycle of Patent Document 1, a refrigerant on a downstream side of an evaporator is drawn from a refrigerant suction port of the ejector by a suction action of a high-speed ejection refrigerant ejected from a nozzle portion of the ejector, a pressure of a mixed refrigerant of the ejection refrigerant and the suction refrigerant is increased by a pressure increase part (diffuser portion) of the ejector, and the refrigerant flows into the accumulator.
With the above configuration, in the ejector-type refrigeration cycle of Patent Document 1, a refrigerant pressure in the accumulator can be increased more than that of a refrigerant evaporation pressure in the evaporator. A consumed power of the compressor is reduced, and a coefficient of performance (COP) of the cycle can be improved in comparison with a general refrigeration cycle device in which a refrigerant evaporation pressure in the evaporator is substantially equal to a drawn refrigerant pressure in a compressor.
Incidentally, a refrigerator oil which is oil for lubricating the compressor is mixed in the refrigerant of a general vapor compression refrigeration cycle including the ejector-type refrigeration cycle, and the refrigerator oil of this type is employed with compatibility to the liquid-phase refrigerant.
For that reason, as in the ejector-type refrigeration cycle of Patent Document 1, in a configuration where the gas-phase refrigerant separated by the accumulator is drawn into the compressor, the refrigerator oil is unlikely to be supplied to the compressor, and an insufficient lubrication of the compressor occurs, and is likely to adversely affect a lifetime of the compressor. When a concentration of the refrigerator oil in the liquid-phase refrigerant separated by the accumulator increases, and the liquid-phase refrigerant high in the concentration of the refrigerator oil flows into the evaporator, the refrigerator oil stays in the evaporator, and is likely to deteriorate a heat exchanging performance of the evaporator.
Therefore, in general, in the refrigeration cycle having the accumulator, a part of the liquid-phase refrigerant separated by the accumulator, and relatively high in the concentration of the refrigerator oil is returned to the gas-phase refrigerant to be drawn to the compressor. As a result, an insufficient lubrication of the compressor is suppressed, and the amount of refrigerator oil flowing into the evaporator is reduced to restrain the refrigerator oil from staying in the evaporator.